any tips?

I’m 14, and I eat so unhealthily. it’s awful. I’m not over weight, or even big, but I want to eat healthy before it’s too late, I know it could affect me in the future. The thing is, it’s so hard, I’m always tempted to eat all the junk food at my house, and I have asked my mom numerous times to buy healthier food, but she rarely does, and I don’t know what to do.